At present, a liquid crystal display is applied widely. In a thin film transistor-liquid crystal display (TFT-LCD), gates of respective transistors of a pixel region are provided with gate driving signals through a gate driving device. In gate driver on array or gate on array (GOA) technique, a gate driving device is formed on an array substrate of a liquid crystal display through array technology, thereby the cost can be reduced and the process is simplified.
The gate driving device formed by adopting the GOA technique comprises multiple stages of shift register circuits, and the respective stages of shift register circuits are connected to different gate lines of transistors of the pixel region. In particular, the respective shift register circuits are connected to gate lines of transistors of a pixel region formed by rows, and controlling, such as turn on or turn off, is performed on transistors of a corresponding row through drive output signals output by the respective stages of shift register circuits. For example, when a certain shift register circuit outputs a drive output signal which is at a high level, a transistor of a row connected thereto is turned on. Then, the turned-on transistor of the row controls brightness according to a signal output by a data driving device.
Additionally, the respective stages of shift register circuits can be composed of a plurality of shift register units. The plurality of shift register units are connected to the gate lines of the transistors of the pixel region formed by rows, so as to perform controlling, such as turn on or turn off, on the transistors of this row. In particular, the respective shift register circuits are composed of two shift register units, which output gate driving signals to the connected gate lines of the transistors of the pixel region alternatively. In the case of performing the alternative driving as described above, when one shift register unit carries out an action and outputs a gate driving signal, the other shift register unit can stop carrying out the action.
As described above, in a liquid crystal display, when the shift register unit cannot operate normally, the liquid crystal display cannot display normally. Therefore, the shift register unit requires higher stability.